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Gov. Bill Richardson of New Mexico once suggested that the Great Lakes -- shown here is Lake Michigan -- might be a source of water for the dry Southwest.

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In reporting a recent story on a fight over water between residents of a small Colorado town and Nestlé WatersNorth America, a bottled water company, I learned much about water scarcity around the world, and the sense — also growing — that shortages of water could spark much future conflict.

That's been the United Nations' position for years – not least because a lack of access to clean water constitutes a huge health problem in much of the developing world. About 1 billion people don't have potable water.

Another reason: water scarcity's potentially destabilizing effects. Many view the conflict in Darfur, for example, as partly motivated by a growing population and a shrinking supply of water.

It's not as though conflicts over water are an entirely new phenomenon. The Pacific Institute keeps a running list of water conflicts [PDF] that stretches back 5,000 years. The first human-on-human conflict over water occurred around 2500 BC in Mesopotamia, according to the list.

A Mesopotamian city state, Lagash, diverted water from its neighbor, Umma. The most recent water conflict: In 2008, the Taliban threatened to blow up Pakistan's Warsak Dam. (The list hasn't been updated for a year.)

Some see evidence of increased risk of conflict in a warming world where some regions are drying.

Rainfall in the area has diminished markedly in the past 50 years, probably due to global warming. In Syria alone, some 300,000 farmers and herders abandoned their homes, families in tow, for urban camps because of the drought. Around 800,000 lost their livelihoods entirely

And that raises an oft-overlooked facet of water scarcity. Experts say that while the potential for international conflict over water certainly exists, international water crises are usually resolved peacefully. The real potential for water conflicts is intra-national (within-country.)

In 2000, for example — an extremely dry year in China — Reuters reported that villagers in Shandong rioted when officials cut off the water they used for irrigation. Several people died.

That same year, officials in the province of Guangdong blew up a water conduit, unintentionally killing six people. Their goal: to stop a nearby county from taking water for a power station.

Likewise, some surmise that China's claim on the Tibetan Plateau may have less to do with its being historically a region of China, the oft-cited justification, than with the China's desire to secure more water.

After all, one-quarter of China is desert. The plateau, meanwhile, has an abundance of glaciers.

The US has its own version of these in-country conflicts. The Southeastern states of Georgia, Alabama, and Florida have longstanding disagreements over water — they are in federal court over water rights — and Georgia Gov. Sonny Perdue has emphasized the state's rights to use water that falls within its borders, despite claims by neighboring Florida and Alabama.

But with continued population growth in the sunny Southwest, the truth may be slightly different.

In 2007, New Mexico Gov. Bill Richardson caused some to gasp when he suggested that water piped in from the Great Lakes might help solve some of the Southwest's water shortage problems.

Hugh McDiarmid Jr. of the Michigan Environmental Council responded in a press release: "Mr. Richardson and his constituents in New Mexico are welcome to reasonable use of Great Lakes water. ... All they have to do is move to the Great Lakes region."